After rebasing my github fork, commits from others are in my pull request

I have created a github fork and made some changes, then created a pull request. After some revisions, I made some additional changes and rebased my fork (and then also my local copy), then committed and pushed it again.

What did I do wrong and how can I fix it? I only changed 3 files (pandas/io/json.py, pandas/io/tests/json/test_json_norm.py and doc/source/whatsnew/v0.18.1.txt (where I also resolved some conflicts after my rebase).